The present invention is based on a method of identifying a target as a friend or foe, the method comprising the following steps:
(1) An interrogator transmits a querying electromagnetic wave to a target to be identified, PA1 (2) Provided that the target to be identified possesses a transponder matched to the querying electromagnetic wave, the target receives the querying electromagnetic wave, if necessary, and the transponder transmits an electromagnetic wave in response, PA1 (3) The responding electromagnetic wave transmitted by the transponder is received and evaluated by the interrogator such that, if a predeterminable transponder response code is present, the associated target to be identified is classified as a friendly target.
The invention is further based on an arrangement for carrying out the method.
Particularly in the military field, but also in civilian applications, for example, for protecting large industrial sites or power stations, it is necessary to identify and/or classify targets need to be identified as friendly or threatening by using electromagnetic waves. In the Identification Friend/Foe (IFF) method, a querying transmitting/receiving arrangement (interrogator) transmits a querying electromagnetic wave, for example by means of a transmitting antenna. If the target is a friendly target, for example, a land, sea or air vehicle belonging to the same military force as the interrogator, the querying electromagnetic wave is received by a transponder on board the friendly target. The transponder then transmits a coded electromagnetic wave as a response. This wave is received and evaluated by the interrogator. The coding is used to decide whether the detected target is to be treated as a friendly target or a threatening or hostile target.
It is evident that, in particular, an interrogator can be detected, localized and attacked very early by a threatening target when the interrogator transmits the querying electromagnetic wave, especially a spatially-nondirectional wave. An obvious solution for avoiding this drawback is for the interrogator to transmit a spatially-directional, querying electromagnetic wave to a predeterminable and unknown target. This type of wave can only be received and evaluated by this target.